Display device and electronic apparatus

ABSTRACT

A display device includes a display section ( 11 ) having a first display surface and a second display surface (S 1 , S 2 ) facing each other. The display section ( 11 ) includes a first display panel ( 111 ) disposed on the first display surface (S 1 ) side, and including a plurality of light emitting elements, and a second display panel ( 112 ) disposed on the second display surface (S 2 ) side, and including a plurality of light control elements each performing light control for control of transmission or reflection of incident light performing reflective image display utilizing the reflection of the incident light.

TECHNICAL FIELD

The present disclosure relates to a display device having a displaysection including two types of display panels, and an electronicapparatus with such a display device.

BACKGROUND ART

Various types of display devices have been proposed conventionally. Forexample, Patent Literature 1 discloses a display device using two typesof display panels (display bodies).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2004-302321

SUMMARY

Meanwhile, in general, display devices are expected to improveconvenience of users. Therefore, suggestion of a technique for improvingconvenience of users is desired.

Accordingly, it is desirable to provide a display device and anelectronic apparatus that are capable of improving convenience of auser.

A display device according to an embodiment of the present disclosureincludes a display section having a first display surface and a seconddisplay surface facing each other. This display section includes a firstdisplay panel disposed on the first display surface side, and includinga plurality of light emitting elements, and a second display paneldisposed on the second display surface side, and including a pluralityof light control elements each performing light control for control oftransmission or reflection of incident light performing reflective imagedisplay utilizing reflection of the incident light.

An electronic apparatus according to an embodiment of the presentdisclosure includes the display device according to the above-describedembodiment of the present disclosure.

In the display device and the electronic apparatus of the embodiments ofthe present disclosure, image display on both of the first and seconddisplay surfaces facing each other is implemented, by utilizing thefirst and second display panels. In addition, since the first displaypanel is configured to include the above-described light emittingelements and the second display panel is configured to include theabove-described light control elements, image display in which thedevice functions on both sides complement each other is implemented.

According to the display device and the electronic apparatus of theembodiments of the present disclosure, the display section having theabove-described first and second display panels is provided, andtherefore, image display on the two display surfaces facing each otheris implemented by allowing the device functions of the respectivedisplay panels to complement each other. Therefore, it is possible toimprove convenience of a user. It is to be noted that, an effectdescribed herein is not necessarily limitative, and may be any ofeffects described in the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic plan view illustrating a configuration example ofan electronic apparatus with a display device, according to anembodiment of the present disclosure.

FIG. 1B is a schematic plan view illustrating a configuration example ofan opposite side of the electronic apparatus illustrated in FIG. 1A.

FIG. 2 is a block diagram schematically illustrating a schematicconfiguration example of the electronic apparatus illustrated in FIG. 1Aand FIG. 1B.

FIG. 3A is a schematic perspective view illustrating a schematicconfiguration example of a display section illustrated in FIG. 2.

FIG. 3B is a schematic perspective view illustrating a schematicconfiguration example of the display section illustrated in FIG. 3A,when viewed from the opposite side.

FIG. 4 is a schematic cross-sectional diagram illustrating a schematicconfiguration example of a pixel including a light emitting elementillustrated in FIG. 3A.

FIG. 5A is a schematic cross-sectional diagram illustrating an exampleof an action in the pixel illustrated in FIG. 4.

FIG. 5B is a schematic cross-sectional diagram illustrating anotherexample of an action in the pixel illustrated in FIG. 4.

FIG. 6 is a schematic cross-sectional diagram illustrating a schematicconfiguration example of a pixel including a light control elementillustrated in FIG. 3B.

FIG. 7A is a schematic cross-sectional diagram illustrating an exampleof an action in the pixel illustrated in FIG. 6.

FIG. 7B is a schematic cross-sectional diagram illustrating anotherexample of an action in the pixel illustrated in FIG. 6.

FIG. 8A is a schematic plan view illustrating a state example in standbyoperation.

FIG. 8B is a schematic plan view illustrating another state example inthe standby operation.

FIG. 9A is a schematic cross-sectional diagram for describing an actionin the state illustrated in FIG. 8A.

FIG. 9B is a schematic cross-sectional diagram for describing an actionin the state illustrated in FIG. 8B.

FIG. 10A is a schematic plan view illustrating an example of a displaymanner when a background is set in a transparent state.

FIG. 10B is a schematic plan view illustrating another example of adisplay manner when a background is set in a transparent state.

FIG. 11A is a schematic cross-sectional diagram for describing an actionin the display manner illustrated in FIG. 10A.

FIG. 11B is a schematic cross-sectional diagram for describing an actionin the display manner illustrated in FIG. 10B.

FIG. 12A is a schematic cross-sectional diagram illustrating an actionin a display manner example when a background is set in a single-colorreflection display state.

FIG. 12B is a schematic cross-sectional diagram illustrating an actionin another display manner example when a background is set in asingle-color display state.

FIG. 13A is a schematic plan view for describing the display mannerillustrated in FIG. 12A.

FIG. 13B is a schematic plan view for describing the display mannerillustrated in FIG. 12B.

FIG. 14 is a schematic plan view illustrating an example of a displaymanner when s display surface is reversed.

FIG. 15 is a schematic plan view illustrating examples of a display modein the case illustrated in FIG. 14.

FIG. 16 is a schematic plan view illustrating another example of adisplay manner when a display surface is reversed.

FIG. 17 is a schematic plan view illustrating examples of a display modein the case illustrated in FIG. 16.

FIG. 18 is a schematic diagram illustrating examples of an adaptationrelationship between various indexes and each display mode.

FIG. 19 is a flowchart illustrating an example of display controlaccording to an embodiment.

FIG. 20 is a flowchart illustrating an example of display controlfollowing FIG. 19.

FIG. 21 is a flowchart illustrating another example of display controlfollowing FIG. 19.

FIG. 22 is a flowchart illustrating an example of display controlfollowing FIG. 21.

FIG. 23 is a flowchart illustrating an example of display controlfollowing FIG. 22.

FIG. 24 is a flowchart, illustrating another example of display controlfollowing FIG. 20 and FIG. 22.

FIG. 25 is a schematic plan view illustrating a configuration example ofan electronic apparatus with a display device according to Modification1.

FIG. 26A is a schematic plan view illustrating a state example in theelectronic apparatus illustrated in FIG. 25.

FIG. 26B is a schematic plan view illustrating a display manner examplein the electronic apparatus illustrated in FIG. 25.

FIG. 26C is a schematic plan view illustrating another display mannerexample in the electronic apparatus illustrated in FIG. 25.

FIG. 27A is a schematic perspective view illustrating a configurationexample of an electronic apparatus with a display device according toModification 2.

FIG. 27B is a schematic perspective view illustrating anotherconfiguration example of the electronic apparatus illustrated in FIG.27A.

MODES FOR CARRYING OUT THE INVENTION

An embodiment of the present disclosure will be described below indetail with reference to the drawings. It is to be noted that thedescription will be provided in the following order.

-   1. Embodiment (an example when a display device is applied to a    mobile apparatus serving as an example of an electronic apparatus)-   2. Modifications

Modification 1 (an example when a display section is configured to befoldable)

Modification 2 (an example when each display panel has flexibility)

-   3. Other modifications

1. Embodiment Configuration Example

FIG. 1A and FIG. 1B each schematically illustrate a configurationexample of an electronic apparatus (an electronic apparatus 1) with adisplay device according to an embodiment of the present disclosure, ina plan view (an X-Y plan view). Specifically, FIG. 1A illustrates anexample of a configuration when viewed from a side where a displaysurface S1 (a first display surface) to be described later is provided,and FIG. 1B illustrates an example of a configuration when viewed from aside where a display surface S2 (a second display surface) to bedescribed later is provided (when viewed from the side opposite to thedisplay surface S1).

In this example, the electronic apparatus 1 serves as, for example, amobile apparatus (a portable apparatus) such as a tablet terminal, asmartphone, and a mobile information terminal (PDA; Personal DigitalAssistant). The electronic apparatus 1 includes a display deviceaccording to the present embodiment in a housing 10, and this displaydevice includes a display section 11.

The display section 11 performs image display based on an image signal(image signals Sv1 and Sv2 to be described later), and has the displaysurfaces S1 and S2 (e.g., two display surfaces on a from side and a backside) facing each other. This display section 11 has a plurality ofpixels (pixels 210 and 220 to be described later) including variousdisplay elements, on the display surfaces S1 and S2. Further, thedisplay section 11 is configured to include, in addition, to thesedisplay elements, components such as a drive device configured byvarious types of TFT (Thin Film Transistor) and the like. In thisexample, this display section 11 is assumed to have an anisotropic shape(a rectangular shape) in which a Y-axis direction (a vertical direction)is a major-axis direction and an X-axis direction (a horizontaldirection) is a minor-axis direction. It is to be noted that, thisdisplay section 11 is configured to include the two types of displaypanels (display bodies), and a detailed configuration example thereofwill be described later (FIG. 2, FIG. 3A, FIG. 3B and so on).

The housing 10 is an outer member that houses both of the displaysurfaces S1 and S2 in the display section 11, winch are thereby visuallyrecognizable. In this example, the housing 10 is assumed to have ananisotropic shape (a rectangular shape) in which a Y-axis direction is amajor-axis direction and an X-axis direction is a minor-axis direction.The display surface S1 side (a bezel region of the display section 11)of the housing 10 is provided with operation sections 12 a, 12 b, and 12c, as illustrated in FIG. 1A. The display surface S2 side (the bezelregion of the display section 11) of the housing 10 is provided with anilluminance sensor 14, as illustrated in FIG. 1B. Further, the housing10 has a gravity position sensor 13 built therein, as illustrated ineach of FIG. 1A and FIG. 1B.

The operation sections 12 a, 12 b, and 12 c each serve as a part (suchas an operation button) to be used when a user operates the electronicapparatus 1. It is to be noted that, instead of providing the operationsections 12 a, 12 b, and 12 c, any type of various touch panels may beprovided on the display section 11 (on a surface of each of the displaysurface S1 side and the display surface S2 side) to serve as anoperation section, thereby allowing the user to operate the electronicapparatus 1.

The gravity position sensor 13 is a sensor that detects a gravityposition of the electronic apparatus 1 (e.g., a posture of theelectronic apparatus 1, such as information indicating which one of thesurfaces of the housing 10 is directed upward). Examples of the gravityposition sensor 13 include an acceleration sensor and a gyro sensor.

The illuminance sensor 14 is a sensor that detects an environmentalilluminance (an illuminance of outside light entering through periphery)corresponding to brightness around the electronic apparatus 1. Thisilluminance sensor 14 is configured to include, for example, componentssuch as various photodiodes having light receiving sensitivity in avisible light region.

Schematic Configuration Example

Next, with reference to FIG. 2. FIG. 3A, and FIG. 3B, a schematicconfiguration example of the electronic apparatus 1 (the display device)will be described. FIG. 2 schematically illustrates a schematicconfiguration example of the electronic apparatus 1, in a block diagram.FIG. 3A schematically illustrates a schematic configuration example ofthe display section 11, in a perspective view, and FIG. 3B schematicallyillustrates a schematic configuration example when the display section11 illustrated in FIG. 3A is viewed from the opposite side, in aperspective view.

The electronic apparatus 1 includes, in addition to the display section11, the operation sections 12 a, 12 b, and 12 c, the gravity positionsensor 13, and the illuminance sensor 14 described above, a displaycontrol section 15 that controls the image display in the displaysection 11, as illustrated in FIG. 2.

(Display Section 11)

The display section 11 is configured by overlaying (affixing together)display panels 111 and 112, along a Z-axis (a thickness direction), asillustrated in FIG. 2.

The display panel 111 (a first display panel) is disposed relatively, onthe display surface S1 side (in a positive direction of the Z-axis), andis configured to output display light Ld1 toward both of a front-surfaceside (the display surface S1 side) and a back-surface side (the displaysurface S2 side) thereof. This display panel 111 has the pixels 210two-dimensionally arranged in a matrix on the display surface S1 (an X-Yplane), for example, as illustrated in FIG. 3A. The pixels 210 eachinclude a light emitting element 211 that performs self-light emission.The light emitting element 211 is configured to emit light (the displaylight Ld1) toward both of the display surface S1 side and the displaysurface S2 side. In the display panel 111, since this light emittingelement 211 is provided as a display element, while display ofrelatively high definition image quality is implemented, powerconsumption at the time of image display is relatively high, as comparedwith the display panel 112 to be described below. It is to be notedthat, a detailed configuration example of this light emitting element211 will be described later (FIG. 4, FIG. 5A, FIG. 5B and so on).

The display panel 112 (the second display panel) is disposed relativelyon the display surface S2 side (in a negative direction of the Z-axis),and is configured to output display light Ld2 toward both of afront-surface side (the display surface S2 side) and a back-surface side(the display surface S1 side) thereof. This display panel 112 has pixels220 two-dimensionally arranged in a matrix on the display surface S2 (anX-Y plane), for example, as illustrated in FIG. 3B. The pixels 220 eachinclude a light control element 221 that performs light control forcontrol of transmission and reflection (control for switching between atransmission state and a reflection state) of incident light. This lightcontrol element 221 also serves as a reflection display element, whichperforms image display (reflective image display) utilizing suchreflection of incident light. The light control element 221 isconfigured to perform such light control and reflective image display,for both of incident light entering from the display surface S1 side andincident light entering from the display surface S2 side. In the displaypanel 112, since this light control element 221 is used as a displayelement, while power consumption at the time of image display isrelatively low, image quality is relatively low, as compared with theabove-mentioned display panel 111. It is to be noted that, a detailedconfiguration example of this light control element 221 will bedescribed later (FIG. 6, FIG. 7A, FIG. 7B and so on).

(Display Control Section 15)

The display control section 15 supplies an image signal (a drivevoltage) to the display section 11 on a pixel-by-pixel basis, therebyperforming the control (performing the display control) allowing theimage display to be performed in this display section 11. Specifically,as will be described later in detail, the display control, section 15individually controls image display (performs individual control ofimage display) in each of the display panels 111 and 112 in the displaysection 11. This display control section 15 has a control section 150and two drive sections 151 and 152, as illustrated in FIG. 2.

The control section 150 controls operation of each of the drive sections151 and 152, based on the image signals Sv1 and Sv2 input from outside,an operation signal Sm supplied from an operation section 12 a, 12 b,and 12 c, a gravity position signal Sg supplied from the gravityposition sensor 13, and an environmental illuminance Di supplied fromthe illuminance sensor 14. Here, the image signal Sv1 corresponds to animage signal for each of the pixels 210 in the display panel 111, andthe image signal Sv2 corresponds to an image signal for each of thepixels 220 in the display panel 112. The operation signal Sm is a signalgenerated according to input operation of the user performed on theoperation sections 12 a, 12 b, and 12 c. The gravity position signal Sgis a signal indicating a detection result (such as posture informationof the electronic apparatus 1) in the gravity position sensor 13. Theenvironmental illuminance Di corresponds to data indicating anenvironmental illuminance detected in the illuminance sensor 14. It isto be noted that, this control section 150 is configured, for example,using a microcomputer.

The drive section 151 supplies a drive voltage Vd1 based on the imagesignal Sv1, to each of the pixels 210 in the display panel 111,according to the control by the control section 150. Similarly, thedrive section 152 supplies a drive voltage Vd2 based on the image signalSv2, to each of the pixels 220 in the display panel 112, according tothe control by the control section 150. These drive sections 151 and 152are each configured using a component such as a semiconductor chipincluding various drive circuits (e.g., a scanning-line driving circuit,a signal-line driving circuit, and a power-line driving circuit).

Here, as will be described later in detail, a light emission quantitychanges for each of the pixels 210 and a light reflection quantitychanges for each of the pixels 220, according to the drive voltage Vd1applied to the light emitting element 211, and the drive voltage Vd2applied to the light control element 221, in the display panels 111 and112, respectively. Further, accompanying such a change in each of thelight emission quantity and a light reflection amount, opticaltransparency changes for each of the pixels 210 and 220. However, acorrespondence between the presence/absence of application of the drivevoltages Vd1 and Vd2 (voltage magnitude), and the presence/absence ofthe optical transparency (degree) is not limited to a correspondence tobe described later, and may be other correspondence (for example, areverse correspondence).

Cross Sectional Configuration Example

Next, a cross sectional configuration example of each of the displaypanels 111 and 112 (the pixels 210 and 220) will be described withreference to FIG. 4, FIG. 5A, FIG. 5B, FIG. 6, FIG. 7A, and FIG. 7B.

(Display Panel 111)

FIG. 4 schematically illustrates a schematic configuration example ofthe display panel 111 (the pixel 210), in a cross-sectional diagram. Thepixels 210 in the display panel 111 are each configured to include thelight emitting element 211 configured by an organic electroluminescence(Electro Luminescence) device (an organic electroluminescence element),in this example.

In this example, the display panel 111 is configured to perform colorimage display, by outputting the display light Ld1 toward both of thedisplay surface S1 side and the display surface S2 side as describedabove, by using a configuration based on a top-surface light emissionsystem (a so-called top emission system). In other words, the pixels 210are each configured to emit the display light 141 corresponding to, forexample, any one of red (R), green (G), and B (blue) in three primarycolors.

The light emitting element 211 (the organic EL device) in each of thepixels 210 is sealed on a drive substrate 30 by a sealing substrate 37.In each of the light emitting elements 211, an inter-pixel insulatingfilm 32, an organic layer 33, and a second electrode (an upperelectrode) 34 are laminated in this order on a first electrode (a lowerelectrode) 31. In the display panel 111, a protective film 35 is formedto cover each, of the light emitting elements 211, and, on thisprotective film 35, the sealing substrate 37 is laminated with a blackmatrix 36 interposed therebetween. The organic layer 33 includes layerssuch as a hole injection layer, a hole transport layer, a light emittinglayer, and an electron transport layer, which are not illustrated. Ofthese, the light emitting layer is a layer that emits color lightdifferent for each of the pixels 210 corresponding to theabove-described three primary colors (a red light emitting layer, agreen light emitting layer, or a blue light emitting layer), and iscolored for each of these pixels 210, to form a predetermined pattern.Further, in a region between the pixels 210 on the protective film 35,the black matrix 36 is provided.

It is to be noted that, for example, a color filter corresponding to theabove-described three primary colors may be provided on at least one ofthe display surface S1 side (the upper part) and the display surface S2side (the lower part) of the light emitting element 211, for purposessuch as making an improvement in contrast at the time of Image display.Further, in this example, the display panel 111 is configured based onthe top-surface light emission system, but is not limited to thissystem, and may be configured based on, for example, a bottom-surfacelight emission system (a so-called bottom emission system).

Here, in the display panel 111, each of the layers is configured using alight transmissive material (a transparent material) so that at least apart thereof exhibits optical transparency (transparency) in each of thelayers described above. Specifically, the drive substrate 30 and thesealing substrate 37 are each configured using, for example, a substratesuch as a glass substrate and a light-transmissive resin substrate.Further, the first electrode 31, the second electrode 34, and componentssuch, as an electrode and wiring of each of the devices on the drivesubstrate 30 are each made of for example, a transparent oxidesemiconductor such as ITO, IZO (Indium Zink Oxide), and AZO (AluminumZink Oxide), or a light transmissive material such as transparentcarbon. The layers such as the organic layer 33 and the protective film35 are also each made of various light transmissive materials.

In the display panel 111 having such a configuration, the light emissionquantity changes for each of the pixels 210, according to the drivevoltage Vd1 applied to each of the light emitting elements 211. Further,a light transmission quantity also changes accompanying such a change inthe light emission quantity, and as a result, the optical transparencychanges for each of the pixels 210.

Specifically, when the drive voltage Vd1 is not applied to the lightemitting element 211 (or the voltage value thereof is small) in thepixel 210, both of outside light Le entering from the display surface S1side and outside light Le entering from the display surface S2 side passthrough the pixel 210, for example, as illustrated in FIG. 5A. In otherwords, at this time, the corresponding pixel 210 in the display panel111 exhibits the optical transparency (transparency), and thus in atransparent state.

On the other hand, for example, as illustrated in FIG. 5B, when thedrive voltage Vd1 is applied to the light emitting element 211 (or thevoltage value thereof is large) in the pixel 210, the emission light(the display light Ld1) is output toward both of the display surface S1side and the display surface S2 side from the light emitting element 211as described above. In other words, at this time, the correspondingpixel 210 in the display panel 111 does not exhibit the opticaltransparency, and thus in a non-transparent state (in a display statebased on the display light Ld1).

(Display Panel 112)

FIG. 6 schematically illustrates a schematic configuration example ofthe display panel 112 (the pixel 220), in a cross-sectional diagram. Inthis example, the pixels 220 in the display panel 112 are eachconfigured to include the light control element 221 configured by aliquid crystal device including a cholesteric liquid crystal.

The display panel 112 also performs color image display, as with thedisplay panel 111. In other words, the pixels 220 are each configured tooutput the display light Ld2 corresponding to any one of red (R), green(G), and B (blue) in the three primary colors, for example.

In this display panel 112, between a drive substrate 40 and atransparent substrate 45, a pixel electrode 41, a liquid crystal layer42, a common electrode 43, and a black matrix 44M or a color filter 44Care provided in this order from the drive substrate 40 side. The colorfilter 44C is disposed for each of the pixels 220, and the black matrix44M is disposed in a region between the pixels 220. The liquid crystallayer 42 is configured by the cholesteric liquid crystal. Of these, thepixel electrode 41, the liquid crystal layer 42, and the commonelectrode 43 are used to configure the light control element 221 (theliquid crystal device).

Here, in the display panel 112, as with the display panel 111, each ofthe layers is configured using a light transmissive material so that atleast a part thereof exhibits the optical transparency in each of thelayers described above. Specifically, the drive substrate 40 and thetransparent substrate 45 are each configured using, for example, asubstrate such as a glass substrate and a light-transmissive resinsubstrate. Further, for example, the pixel electrode 41, the commonelectrode 43, and components such as an electrode and wiring of each ofthe devices on the drive substrate 40 are each made of, for example, atransparent oxide semiconductor such as ITO, IZO, and AZO, or a lighttransmissive material such as transparent carbon.

In the display panel 112 (the pixel 220) having such a configuration,the light reflection quantity changes for each of the pixels 220,according to the drive voltage Vd2 applied to each of the light controlelements 221. Further, a light transmission quantity also changesaccompanying such a change in the light emission quantity, and as aresult, the optical transparency changes for each of the pixels 220, aswith the display panel 111.

Specifically, when the drive voltage Vd2 is not applied to the lightcontrol element 221 (or the voltage value thereof is small) in the pixel220, both of the outside light Le entering from the display surface S1side and the outside light Le entering from the display surface S2 sidepass through the pixel 220 (the light control element 221), for example,as illustrated in FIG. 7A. In other words, at this time, thecorresponding pixel 220 in the display panel 112 exhibits the opticaltransparency (transparency), and thus in a transparent state.

On the other hand, for example, as illustrated in FIG. 7B, when thedrive voltage Vd2 is applied to the light control element 221 (or thevoltage value thereof is large) in the pixel 220, the following occurs.That is, in the pixel 220 (the light control element 221), the lightcontrol for causing reflection is performed, for both of the incidentlight (such as the outside light Le) entering from the display surfaceS1 side and the incident light (such as the outside light Le) enteringfrom the display surface S2 side, as described above. As a result, thedisplay light Ld2 based on the incident light is output toward both ofthe display surface S1 side and the display surface S2 side, so that thereflective image display is performed. In other words, at this time, thecorresponding pixel 220 in the display panel 112 does not exhibit theoptical transparency, and thus in a non-transparent state (in a displaystate based on the display light Ld2).

Action and Effect

(A. Basic Operation)

In this electronic apparatus 1 (the display device), the image signalsSv1 and Sv2 for the display panels 111 and 112 are each supplied to thecontrol section 150 in the display control section 15, for example, asillustrated in FIG. 2. Further, the operation signal Sm from theoperation sections 12 a, 12 b, and 12 c, the gravity position signal Sgfrom the gravity position sensor 13, and the environmental illuminanceDi from the illuminance sensor 14 are each supplied to this controlsection 150. The control section 150 controls operation of each of thedrive sections 151 and 152, based on the image signals Sv1 and Sv2, theoperation signal Sm, the gravity position signal Sg, and theenvironmental illuminance Di. The drive sections 151 and 152 supply thedrive voltages Vd1 and Vd2 based on the image signals Sv1 and Sv2,according to the control by this control section 150, to the pixels 210and 220 in the display panels 111 and 112, respectively.

In this way, the image display in each of the display panels 111 and 112is individually controlled by the display control section 15 (theindividual control of the image display is performed). Further, thedisplay panel 111 is disposed relatively on the display surface S1 side,and outputs the display light Ld1 toward both of the display surface S1side and the display surface S2 side. Furthermore, the display panel 112is disposed relatively on the display surface S2 side, and outputs thedisplay light Ld2 toward both of the display surface S1 side and thedisplay surface S2 side. As a result, in this electronic apparatus 1(the display device), by utilizing these two types of the display panels111 and 112, the image display (double-sided display) is implemented onboth of the display surfaces S1 and S2 facing each other.

(B. Summary of Action in Each Operation)

Next, a summary of an action in each operation (standby operation andimage display operation) of the electronic apparatus 1 (the displaydevice) will be described with reference to figures including FIG. 8A toFIG. 13B.

(In Standby Operation)

First, in the standby operation (in a standby state) of the electronicapparatus 1, the display control is performed so that pixel regions(regions where the pixels 210 and 220 are disposed) in the respectivedisplay panels 111 and 112 are both in the transparent state, forexample, as illustrated in FIG. 8A and FIG. 8B. In other words, thedisplay control section 13 performs the display control so that thepixel regions in the respective display panels 111 and 112 are both inthe transparent state, when the electronic apparatus 1 being in thestandby state is detected based on the signal such as the operationsignal Sm.

It is to be noted that, an example illustrated in FIG. 8A represents astate where the user holds the electronic apparatus 1 being in thestandby state with a hand h so that the display surface S1 faces upward.Further, an example illustrated in FIG. 8B represents a state where theuser holds the electronic apparatus 1 being in the standby state withthe hand b so that the display surface S2 faces upward.

Here, in the example in each of FIG. 8A and FIG. 8B, the display controlsection 15 supplies neither the drive voltage Vd1 to the pixels 210 inthe display panel 111, nor the drive voltage Vd2 to the pixels 220 inthe display panel 112, for example, as illustrated in FIG. 9A and FIG.9B. Therefore, in each of the display panels 111 and 112, both of theoutside light Le entering from the display surface S1 side and theoutside light Le entering from the display surface S2 side pass througheach of the pixels 210 and 220, as described above. As a result all thepixels 210 and 220 in the display panels 111 and 112 exhibit the opticaltransparency, and thus in the transparence state illustrated in FIG. 8Aand FIG. 8B.

In this way, in the standby state of the electronic apparatus 1 (thedisplay device), the display section 11 is in the transparent state (atransparent panel), when viewed from either of the display surface S1side and the display surface S2 side. Therefore, a display design withan advanced brightness impression can be implemented.

(In Image Display Operation: Background Being in Transparent State)

Next in the image display operation of the electronic apparatus 1, thereis, as a first example, a case where a part of the display section 11displays an image, while a background part of the image is in thetransparent state, for example, as illustrated in FIG. 10A and FIG. 10B.In other words, the display control section 15 performs, the displaycontrol in the display panels 111 and 112, to allow such a partial imagedisplay state and transparent state, when an instruction for settingsuch a display mode is provided.

It is to be noted that, the example illustrated in FIG. 10A represents astate where the user holds the electronic apparatus 1 with the hand h sothat the display surface S1 faces upward, while an image (a letter “A”)is displayed on a portion of the display surface S1 of the electronicapparatus 1. Further, the example illustrated in FIG. 10B represents astate where the user holds the electronic apparatus 1 with the hand h sothat the display surface S2 faces upward, while an image (a letter “B”)is displayed on a portion of the display surface S2 of the electronicapparatus 1.

At this time, in the example in FIG. 10A, the display control section 15performs the following display control in the display panel 111, forexample, as illustrated in FIG. 11A. That is, the drive voltage Vd1 issupplied to the pixel 210 in a display pixel region, whereas the drivevoltage Vd1 is not supplied to the pixel 210 in a background region (anon-display pixel region). On the other hand, in this first example, thedisplay control section 15 does not supply the drive voltage Vd2 to allthe pixels 220 in the display panel 112. Therefore, in the displaypixel, region in the display panel 111, the emission light (the displaylight Ld1) is output from the light emitting element 211 toward both ofthe display surface S1 side and the display surface 82 side as describedabove, and thus the non-transparent state is established. Meanwhile, inthe background region in the display panel 111, both of the outsidelight Le entering from the display surface S1 side and the outside lightLe entering from the display surface S2 side pass therethrough asdescribed above, and thus the transparent state is established. On theother hand, in the display panel 112, both of the outside light Leentering from the display surface S1 side and the outside light Leentering from the display surface S2 side as described above passthrough all the pixels 220, and thus the transparent state isestablished. In this way, as illustrated in FIG. 10A, when the displaysurface S1 faces upward, the partial image display state and thetransparent state of the display section 11 are implemented. It is to benoted that, in this case, the display light Ld1 is output toward both ofthe display surfaces S1 and S2, and therefore, the image display (theletter “A”) is visibly recognizable not only from the display surface S1side (the upper side) but also from the display surface S2 side (thelower side).

On the other hand, in the example in FIG. 10B, the display controlsection 15 performs the following display control in the display panel112, for example, as illustrated in FIG. 11B. That is, the drive voltageVd2 is supplied to the pixel 220 in a display pixel region, whereas thedrive voltage Vd2 is not supplied to the pixel 220 in a backgroundregion (a non-display pixel region). On the other hand, in this firstexample, the display control section 15 does not supply the drivevoltage Vd1 to all the pixels 210 in the display panel 111. Therefore,in the display pixel region in the display panel 112, as for theincident light (such as the outside light Le) entering from both, of thedisplay surfaces S1 and S2 sides, the display light Ld2 based on theincident light is output toward tire display surface S1 side and thedisplay surface S2 side as described above, and the reflective imagedisplay is performed. In other words, since the incident light isreflected, the display pixel region 210 is in the non-transparent state.Meanwhile, in the background region in the display-panel 112, both ofthe outside light Le entering from the display surface S1 side and theoutside light Le entering from the display surface S2 side passtherethrough as described above, and thus the transparent state isestablished. On the other hand, in the display panel 111, in all thepixels 210, both of the outside light Le entering from the displaysurface S1 side and the outside light Le entering from the displaysurface S2 side pass therethrough as described above, and thus thetransparent state is established. In this way, the partial image displaystate and the transparent state of the display section 11 areimplemented as illustrated in FIG. 10B, when the display surface S2faces upward. It is to be noted that, in this case as well, the displaylight Ld2 is output toward both of the display surfaces S1 and S2, andtherefore, the image display (the letter “B”) is visibly recognizablenot only from the display surface S2 side (the upper side) but also fromthe display surface S1 side (the lower side).

In this way, in the first example of the image display operation of theelectronic apparatus 1 (the display device), while the display section11 partially displays the image, the display section 11 is in thetransparent state in the background part thereof, when viewed fromeither of the display surface S1 side and the display surface S2 side,as in the standby state described above. Therefore, it is possible toperform necessary image display, while maintaining an advancedbrightness impression to a certain extent.

However, in this first example, the following disadvantage may occurdepending on situation, and thus the convenience of the user maydecrease.

Specifically, in the example (the example where the display surface S1faces upward) illustrated in FIG. 10A and FIG. 11A, the display lightLd1 is emitted from the light emitting element 211 in the display pixelregion toward both of the display surfaces S1 and S2 sides as describedabove, and the display light Ld1 emitted toward the display surface S2side passes through the display panel 112. Therefore, when the displayedimage is viewed from the display surface S1 side (or the display surfaceS2 side), the display luminance in that direction (one side) isrelatively a half (½) value, and thus, contrast may decrease, which maylead to degradation of display image quality.

On the other hand, in the example (the example where the display surfaceS2 faces upward) illustrated in FIG. 10B and FIG. 11B, the reflectiveimage display based on the incident light such as the outside light Leis performed in the light control element 221 in the display pixelregion, as described above. In this case, in a dark environment wherethe outside light Le is little (in a situation where the environmentalilluminance is low), the displayed image is not readily viewed for ishardly visible).

(In Image Display Operation: Background Being in Single-Color ReflectionDisplay State or Single-Color Display State)

Therefore, in the image display operation, of the electronic apparatus1, there is, as a second example, a case where the display controlsection 15 performs the display control, for example, as illustrated inFIG. 12A and FIG. 12B.

It is to be noted that, as with the example in FIG. 10A and FIG. 11A,the example illustrated in FIG. 12A represents a state where the displaysurface S1 faces upward, and the image (the letter “A”) is partiallydisplayed on this display surface S1. In addition, as with the examplein FIG. 10B and FIG. 11B, the example illustrated in FIG. 12B representsa state where the display surface S2 faces upward, and the image (theletter “B”) is partially displayed on this display surface S2.

Here, in the example in FIG. 12A, the display control section 15performs the display control similar to that in the first example (theexample in FIG. 10A and FIG. 11A), in the display panel 111. In otherwords, the drive voltage Vd1 is supplied to the pixel 210 in the displaypixel region, whereas the drive voltage Vd1 is not supplied to the pixel210 in the background region. However, in this second example, unlikethe first example, the display control section 15 supplies the same(common) drive voltages Vd2 to all the pixels 220 in the display panel112. Therefore, the entire pixel region in the display panel 112 is inthe single-color reflection display state (e.g., a full-white displaystate) based on the reflective image display. Accordingly, the displaylight Ld1 emitted front the light emitting element 211 in the displaypixel region toward the display surface S2 side is reflected by thelight control element 221 in the display panel 112, and eventuallyoutput toward the display surface S1 side. In other words, by utilizingthe light control (the light reflection) in the light control element221 in the display panel 112, an effect of reinforcing (supplementing)the contrast in the image display in the display panel 111 (an effect ofimproving utilization efficiency of the display light Ld1) can beobtained.

As a result, for example, as illustrated in FIG. 13A, in this secondexample, when the displayed image is viewed from the display surface S1side, a decrease of the contrast accompanying a decrease of the displayluminance is reduced or evaded, and the display image quality improves(the convenience of the user improves), as compared with the firstexample. If is to be noted that, in this example in FIG. 13A, since theentire pixel region in the display panel 112 is in the single-colorreflection display state, the background part in the display section 11is also in the single-color reflection display state (thenon-transparent state), unlike the first example illustrated in FIG.11A.

On the other hand, in the example in FIG. 12B, the display controlsection 15 performs the display control similar to that in the firstexample (the example in FIG. 10B and FIG. 11B) in the display panel 112.In other words, the drive voltage Vd2 is supplied to the pixel 220 inthe display pixel region, whereas the drive voltage Vd2 is not suppliedto the pixel 220 in the background region. However, in this secondexample, unlike the first example, the display control section 15supplies the same (common) drive voltages Vd1 to all the pixels 210 inthe display panel 111. Therefore, the entire pixel region in the displaypanel 111 is in the single-color display state (e.g., a full-whitedisplay state or a specific-color display state) based on the lightemission of the light emitting element 211. In other words, the displaylight Ld1 output from the display panel 111 (toward the display surfaceS1 side) can be supplementally utilized in the image display in thedisplay panel 112, so that this display panel 111 serves as an auxiliarylight source (a backlight).

As a result, in this second example, unlike the first example, when thedisplayed image is viewed from the display surface S2 side, for example,as illustrated in FIG. 13B, the displayed image is readily viewed (theconvenience of the user improves), even in a dark environment where theoutside light Le is little (in a situation where the environmentalilluminance is low). It is to be noted that, in this example in FIG. 13Bas well, since the entire pixel region in the display panel 111 is inthe single-color display state, the background, part in the displaysection 11 is also in the single-color display state (thenon-transparent state), unlike the first example illustrated in FIG.11B.

In this way, when, the second example is used in the image display, thefunction (a device function) of the light emitting element 211 in thedisplay panel 111 and the function of the light control element 221 inthe display panel 112 complement each other, thereby implementing theimage display on the display surfaces S1 and S3 (the double-sideddisplay). As a result, an improvement of convenience to the user can beexpected.

(C. A Plurality of Types of Display Modes)

Next a plurality of types (six types, in this example) of display modessettable in the electronic apparatus 1 (the display device) will bedescribed with reference to figures including FIG. 14 to FIG. 18. Inother words, the display control section 15 performs the individualcontrol of the image display in each of the display panels 111 and 112,to execute one display mode selected from the plurality of types ofdisplay modes utilizing a change in the optical transparency for each ofthe pixels 210 and 220 described above.

It is to be noted that, as will be described later in detail, such adisplay mode can be arbitrarily set (selected, or switched), dependingon, for example, power saving, ambient light environment, screen designor image quality preference (selectivity), image type, and so on. Inaddition, for the way of making such a selection, there may be utilizedonly one of, or a combination of, manual selection, (manual control)utilizing input operation performed by the user on the operationsections 12 a, 12 b, and 12 c, and automatic selection (automaticcontrol) utilizing information such as a detection result in theilluminance sensor 14 to be described later.

(First to Third Display Modes: Display Surface S1 Facing Upward)

First, three types of display modes (first to third display modes) amongthe above-described six types of display modes will be described withreference to figures including FIG. 14 and FIG. 15. These first to thirddisplay modes are each provided as a display mode to be set when thedisplay surface S1 facing upward is detected, as will be describedbelow.

Here, the description will be provided using, as an example, a casewhere the electronic apparatus 1 (the display device) is reversed(turned upside down), by being changed from a state where the displaysurface S2 faces upward as illustrated in, for example, Part (A) of FIG.14, to a state where the display surface S1 faces upward as illustratedin, for example, Part (B) of FIG. 14 (see an arrow P11 in FIG. 14).

In this case, when occurrence of a change from the state where thedisplay surface S2 faces upward to the state where the display surfaceS1 faces upward is determined, by the gravity position signal Sgobtained in the gravity position sensor 13, the display control section15 performs the display control as follows. That is, control ofswitching the image display from a state of displaying the image (thepartial display of displaying the letter “B” in this example) in thedisplay panel 112 on the display surface S2 side as illustrated in, forexample, Part (A) of FIG. 14, to a state of displaying the identicalimage is the display panel 111 on the display surface S1 side asillustrated in, for example, Part (B) of FIG. 14.

It is to be noted that, at this time, for example, the followinginformation may be temporarily displayed on the display section 11 (thedisplay surface S1), as indicated by, for example, a reference numeralP12 in Part (B) of FIG. 14. That is, for example, information indicating“power consumption increasing” or “high definition image quality modestarting”, due to switching from the image display state in the displaypanel 112 to the image display state in the display panel 111, may betemporarily displayed. In addition, index information of powerconsumption (e.g., information, such as a built-in battery duration inthe electronic apparatus 1) in the selected display mode may bedisplayed on the display section 11 (the display surface S1). When thesekinds of information are displayed, useful information is provided tothe user, and therefore, a further improvement of convenience to theuser can be expected.

Further, when the image display (the display light Ld1 being outputtoward both of the display surface S1 and S2 sides) by the lightemitting element 211 is thus performed in at least a part of the pixelregion in the display panel 111 on the display surface S1 side, thedisplay control section 15 performs the following display control. Thatis, the individual control of the image display in each of the displaypanels 111 and 112 is performed to execute (set) one display modeselected from the first to third display modes to be described below.

Here, when the first display mode is set, an image is displayed asillustrated in, for example, Part (A) of FIG. 15. Specifically, in thedisplay panel 111 on the display surface S1 side (the front side), thedisplay control section 15 performs the display control so that theimage display is performed by utilizing the emission state by the lightemitting element 211, as described above. On the other hand, in thedisplay panel 112 on the display surface S2 side (the back side), thedisplay control section 15 performs the display control so that theentire pixel region of the display panel 112 is in the transparent state(a light transmission state), by utilizing the transmission of theincident light (such as the outside light Le) by the light controlelement 221. In other words, this first display mode corresponds to theexample in FIG. 10A and FIG. 11A described above (the first example inthe image display).

In this first display mode, while the display section 11 (the displaysurface S1) partially displays the image, the display section 11 is inthe transparent state is the background part thereof, when viewed fromeither of the display surface S1 side and the display surface S2 side,as described above. Therefore, it is possible to perform necessary imagedisplay, while maintaining an advanced brightness impression to acertain extent.

Further, when the second display mode is set, an image is displayed asillustrated in, for example, Part (B) of FIG. 15. Specifically, for thedisplay panel 111 on the display surface S1 side, the display controlsection 15 performs the display control in a manner similar to that inthe first display mode. On the other hand, in the display panel 112 onthe display surface S2 side, the display control section 15 performs thedisplay control so that the entire pixel region of the display panel 112is in the single-color reflection display state, by utilizing thereflective image display based on the incident light (such as thedisplay light Ld1, and the outside light Le) by the light controlelement 221. In other words, this second display mode corresponds to theexample in FIG. 12A and FIG. 13A described, above (the second example inthe image display).

In this second display mode, as described above, when the displayedimage is viewed from the display surface S1 side, a decrease of thecontrast accompanying a decrease of the display luminance is reduced orevaded, and as a result, the display image quality improves and thus theconvenience of the user improves, as compared with the first displaymode.

When the third display mode is set, an image is displayed as illustratedin, for example, Part (C) of FIG. 15. Specifically, for the displaypanel 111 on the display surface S1 side, the display control section 15performs the display control in a manner similar to that of each of thefirst and second modes. On the other hand, in the display panel 112 onthe display surface S2 side, the display control is performed toestablish the partial single-color reflection display state and thetransparent state. Specifically, the display control is performed sothat a vicinity of a pixel region corresponding to (facing) the displaypixel region in the display panel 111 is in the single-color reflectiondisplay state, on a principle similar to that in the second displaymode. In addition, the display control is performed so that anon-display pixel region (a transparent pixel region or backgroundregion) vicinity in the display panel 111 is in the transparent state,on a principle similar to that in the first display mode. In otherwords, in this third display mode, the partial single-color reflectiondisplay in the display panel 112 on the back side is performed byestablishing association with the displayed image in the display panel111 on the front side.

In this third display mode, first, as with the first display mode, whilethe display section 11 (the display surface S1) partially displays theimage, the display section 11 is in the transparent state in thebackground part thereof when viewed from either of the display surfaceS1 side and the display surface S2 side. Further, in the display pixelregion, the image display by selective superposition in both of thedisplay panels 111 and 112 is performed and thus, an effect of improvingthe contrast on a principle similar to that in the second display modeis selectively obtained in the display pixel region. Therefore,advantages of both of the first and second display modes are achievable,which makes it possible to perform necessary image display of highdefinition image quality, while maintaining an advanced brightnessimpression to a certain extent. As a result, in this third display mode,a further improvement of convenience to the user can be expected.

Here, such selection of one display mode from the first to third displaymodes is set for example, according to the operation, signal Sm obtainedby the input operation performed on the operation sections 12 a, 12 b,and 12 c as described above. In addition, other setting, such as settingof color (for example, an arbitrary color other than white describedabove, such as red, green, and blue) in the single-color reflectiondisplay state in the display panel 112 in the second and third displaymodes, and setting of the portion of the pixel region to be in thesingle-color reflection display state or the transparent state in thethird display mode, may also be arbitrarily adjustable (settable)according to this operation signal Sm. In such a case, these kinds ofsetting are arbitrarily adjustable according to preference of the useror a use environment, and therefore, a further improvement ofconvenience to the user can be expected.

In this way, in the electronic apparatus 1, when the display surface S1facing upward is detected, any of the first to third display modes isarbitrarily suitable according to, for example, various indexes to bedescribed later, and therefore, a further improvement of convenience tothe user can be expected.

(Fourth to Sixth Display Modes: Display Surface S2 Facing Upward)

Next, the remaining three types of display modes (the fourth to sixthdisplay modes) among the six types of display modes described above willbe described with reference to figures including FIG. 16 and FIG. 17.These fourth to sixth display modes are each provided as a display modeto be set when the display surface S2 facing upward is detected, as willbe described below.

Here, the description will be provided using, as an example, a casewhere the electronic apparatus 1 (the display device) is reversed(turned upside down), by being changed from a state where the displaysurface S1 faces upward as illustrated in, for example, Part (A) of FIG.16, to a state where the display surface S2 faces upward as illustratedin, for example, Part (B) of FIG. 16 (see an arrow P21 in FIG. 16).

In this case, when occurrence of a change from the state where thedisplay surface S1 faces upward to the state where the display surfaceS2 faces upward is determined by the gravity position signal Sg obtainedin the gravity position sensor 13, the display control section 15performs the display control as follows. That is, control of switchingthe image display, from a state of displaying the image (the partialdisplay of displaying the letter “A” in this example) in the displaypanel 111 on the display surface S1 side as illustrated in, for example,Part (A) of FIG. 16, to a state of displaying the identical image in thedisplay panel 112 on the display surface S2 side as illustrated in, forexample, Part (B) of FIG. 16.

It is to the noted that, at this time, for example, the followinginformation may be temporarily displayed on the display section 11 (thedisplay surface S2), as indicated by, for example, a reference numeralP22 in Part (B) of FIG. 16. That is, for example, information indicating“power consumption decreasing” or “carry mode starting”, due toswitching from the image display state in the display panel 111 to theimage display state in the display panel 112, may be temporarilydisplayed. Further, in this case as well, as described above, the indexinformation of power consumption in the selected display mode may bedisplayed on the display section 11 (the display surface S2).Furthermore, in this case, an index value of the environmentalilluminance Di detected by the illuminance sensor 14 may be displayed onthe display section 11 (the display surface S2). When these kinds ofinformation are displayed, useful information is provided to the user,and therefore, a further improvement of convenience to the user can beexpected.

Further, when the reflective image display (the display light Ld2 beingoutput toward both, of the display surface S1 and S2 sides) by the lightcontrol element 221 is thus performed in at least a part of the pixelregion in the display panel 112 on the display surface S2 side, thedisplay control section 15 performs the following display control. Thatis, the individual control of the image display in each of the displaypanels 111 and 112 is performed, to execute (set) one display modeselected from the fourth to sixth display modes to be described below.

Here, when the fourth display mode is set, an image is displayed asillustrated in, for example, Part (A) of FIG. 17. Specifically, is thedisplay panel 112 on the display surface S2 side (the front side), thedisplay control section 15 performs the display control so that thereflective image display is performed (become the light reflectionstate) by utilizing the reflection of the incident light (such as theoutside light Le) by the light control element 221, as described above.On the other hand, in the display panel 111 on the display surface S1side (the back side), the display control section 15 performs thedisplay control so that the entire pixel region of the display panel 111is in the transparent state (a light transmission state), by utilizingthe non-emission state (a light extinction state) by the light emittingelement 211. In other words, this fourth display mode corresponds to theexample in FIG. 10B and FIG. 11B described above (the first example inthe image display).

In this fourth display mode, while the display section 11 (the displaysurface S2) partially displays the image, the display section 11 is inthe transparent state in the background part thereof, when viewed fromeither of the display surface S1 side and the display surface S2 side,as described above. Therefore, it is possible to perform necessary imagedisplay, while maintaining an advanced brightness impression to acertain extent.

Further, when the fifth display mode is set, an image is displayed asillustrated in, for example, Part (B) of FIG. 17. Specifically, for thedisplay panel 112 on the display surface S2 side, the display controlsection 15 performs the display control in a manner similar to that inthe fourth display mode. On the other hand, in the display panel 111 onthe display surface S1 side, the display control section 15 performs thedisplay control so that the entire pixel region of the display panel 111is in the single-color display state, by utilizing the emission state (alighting state) by the light emitting element 211. In other words, thisfifth display mode corresponds to the example in FIG. 12B and FIG. 13Bdescribed above (the second example in the image display).

In this fifth display mode, as described above, the display panel 111serves as the auxiliary light source. Therefore, unlike the fourthdisplay mode, when the displayed image is viewed from the displaysurface S2 side, the displayed image is readily viewed even in a darkenvironment where the outside light Le is little and thus, theconvenience of the user improves. Moreover, it is possible to implementan effect such as making the displayed image viewed from the displaysurface S2 side and the displayed image viewed from the display surfaceS1 side different from each other in terms of image feeling.

When the sixth display mode is set an image is displayed as illustratedin, for example, Part (C) of FIG. 17. Specifically, for the displaypanel 112 on the display surface S2 side, the display control section 15performs the display control in a manner similar to that of each of thefourth and fifth modes. On the other hand, in the display panel 111 onthe display surface S1 side, the display control is performed toestablish the partial single-color display state and the transparentstate. Specifically, the display control is performed so that a vicinityof a pixel region corresponding to (facing) the display pixel region inthe display panel 112 is in the single-color display state, on aprinciple similar to that in the fifth display mode. In addition, thedisplay control is performed so that a non-display pixel region (atransparent pixel region or background region) vicinity in the displaypanel 112 is in the transparent state, on a principle similar to that inthe fourth display mode. In other words, in this sixth display mode, thepartial single-color display in the display panel 111 on the back sideis performed by establishing association with the displayed image in thedisplay panel 112 on the front side.

In this sixth display mode, first, as with the fourth display mode,while the display section 11 (the display surface S2) partially displaysthe image, the display section 11 is in the transparent state in thebackground part thereof, when viewed from either of the display surfaceS1 side and the display surface S2 side. Further, as with the fifthdisplay mode, when the displayed image is viewed from the displaysurface S2 side, the displayed image is readily viewed, even in a darkenvironment where the outside light Le is little. Furthermore, in thisdisplay pixel region, the image display by selective superposition inboth of the display panels 111 and 112 is performed and thus, an effectof improving the contrast can also be expected. Therefore, advantagesand the like in both of the fourth, and fifth display modes areachievable, which makes it possible to perform necessary image displayof high definition image quality, even in a dark environment, whilemaintaining an advanced brightness impression to a certain extent. As aresult, in this sixth display mode, a further improvement of convenienceto the user can be expected.

Here, such selection of one display mode from the fourth to sixthdisplay modes is set, for example, according to the operation signal Smobtained by the input operation performed on the operation sections 12a, 12 b, and 12 c, or the environmental illuminance Di detected by theilluminance sensor 14, as described above. In addition, other setting,such as setting of color (for example, white, red, green, and blue) inthe single-color display state in the display panel 111 in the fifth andsixth display modes, and setting of the portion of the pixel region tobe in the single-color display state or the transparent state in thesixth display mode, may also be arbitrarily adjustable (settable)according to this operation signal Sm. In such a case, these kinds ofsetting are arbitrarily adjustable according to preference of the useror a use environment, and therefore, a further improvement ofconvenience to the user can be expected.

In this way, in the electronic apparatus 1, when the display surface S2facing upward is detected, any of the fourth to sixth display modes isarbitrarily settable according to, for example, various indexes to thedescribed later, and therefore, a further improvement of convenience tothe user can be expected.

(Adaptation Relationship between Various indexes and Each Display Mode)

Here, Part (A) to Part (D) of FIG. 18 each schematically illustrate anexample of an adaptation relationship between various indexes and eachdisplay mode. It is to be noted that, each index described here is onlyan example, and other indexes may be utilized in selecting the displaymode.

First Part (A) of FIG. 18 illustrates an example of a correspondencewith each display mode, for adaptability to presence/absence of anexternal power supply (power saving) of the electronic apparatus 1. Itis to be noted that, in this example, each of use in a house (theexternal power supply being present) and use in a garden or on a train(the external power supply being absent and battery driving being used)is illustrated, by being associated, with the display modes assumed tobe suitable.

As illustrated in this Part (A) of FIG. 18, it may be said that it isdesirable to perform the image display giving priority to image quality,by utilizing the display mode (the first to third display modes) ofallowing visual recognition with the display surface S1 (the displaypanel 111 including the light emitting element 211) facing upward, whenthe external power supply is present. On the other hand, when theexternal power supply is absent (the battery driving), it may be said,that it is desirable to perform the image display giving priority topower saving and mobility, by utilizing the display mode (the fourth tosixth display modes) of allowing visual recognition with the displaysurface S2 (the display panel 112 including the light control element221) facing upward. By thus setting the display mode, the image displayadapted to the presence/absence of the external power supply (powersaving) can be implemented.

Further, Part (B) of FIG. 18 illustrates an example of a correspondencewith each display mode, for adaptability to ambient light environment inusing the electronic apparatus 1. It is to be noted that, in thisexample, each of use in darkness (when the environmental illuminance islow), and use in a room during the daytime or in direct sunlight (whenthe environmental illuminance is high) is illustrated, by beingassociated with the display modes assumed to be suitable.

As illustrated in this Part (B) of FIG. 18, it may be said that it isdesirable to perform the image display based on self-light emission, byutilizing the display mode (the first to third display modes) ofallowing visual recognition with the display surface S1 (the displaypanel 111 including the light emitting element 211) facing upward, whenthe environmental illuminance is low (in a dark light environment). Onthe other hand, when the environmental illuminance is high (in a brightlight environment), it may be said that it is desirable to perform thereflective image display, by utilizing the display mode (the fourth tosixth display modes) of allowing visual recognition with the displaysurface S2 (the display panel 112 including the light control element221) facing upward. By thus setting the display mode, the image displayadapted to the ambient light environment can be implemented.

Part (C) of FIG. 18 illustrates an example of a correspondence with eachdisplay mode, for adaptability to unique design and unique expressionpreference (fashionability) in the electronic apparatus 1 (the displaysection 11). It is to be noted that, in this example, each of orthodoxfashion, uniqueness emphasizing fashion, and sparkling-effect expressingfashion is illustrated, by being associated with the display modesassumed to be suitable.

As illustrated in this Part (C) of FIG. 18, it may be said that thesecond and fifth display modes in which the background part is in thesingle-color reflection display state or the single-color display suiteare relatively orthodox display modes. Meanwhile, it may be said thatthe fourth and sixth display modes in which the reflective image displayis performed and the background part is basically in the transparentstate are relatively unique display modes. Further, it may be said thatthe first and third display modes in which the image display based onself-light emission is performed and the background part is basically inthe transparent state are sparkling-effect expressing display modes. Bythus setting the display mode, the image display adapted to varioustypes of fashionability can be implemented.

Part (D) of FIG. 18 illustrates an example of a correspondence with eachdisplay made, for adaptability to the type of an image displayed in theelectronic apparatus 1 (the display section 11). It is to be noted that,in this example, each of a case of an image (a still image) for pictureappreciation, a case of an image (a moving image of not-so-quickmovement) for a movie, and a case of a sports moving image (a movingimage of fast movement) is illustrated, by being associated with thedisplay modes assumed to be suitable.

As illustrated in this Part (D) of FIG. 18, it may be said that it isdesirable to perform the image display based on self-light emission, byutilizing the display mode (the first to third display modes) ofallowing visual recognition with the display surface S1 (the displaypanel 111 including the light emitting element 211) facing upward, inthe case of the moving image. On the other hand, in the case of thestill image, it may be said that it is desirable to perform thereflective image display, by utilizing the display mode (the fourth tosixth display modes) of allowing visual recognition, with the displaysurface S2 (the display panel 112 including the light control element221) facing upward. By thus setting the display mode, the image displayadapted to the type of the displayed image can be implemented.

(D. Specific Example of Display Control)

Next, a specific example (an example of a series of steps in the displaycontrol performed after the power supply of the electronic apparatus 1enters an ON state and before the power supply enters an OFF state) ofthe display control in the electronic apparatus 1 (the display device)will be described with reference to FIG. 19 to FIG. 24.

FIG. 19 to FIG. 24 illustrate an example of this series of steps in thedisplay control by the display control section 15 (mainly the controlsection 150), in a flowchart.

When the power supply of the electronic apparatus 1 enters the on (ON)state, first, the display control section 15 acquires the gravityposition signal Sg from the gravity position sensor 13 (step S101 ofFIG. 19). Next, based on this gravity position signal Sg, the displaycontrol section 15 determines whether the display surface S1 is in thestate of facing upward (step S102). Here, when the display surface S1 isdetermined not to be in the state of facing upward (the other surface isin the state of facing upward) (step S102: N), the flow proceeds to stepS114 (FIG. 21) to be described later.

On the other hand, when the display surface S1 is determined to be inthe state of facing upward (step S112: Y), the display control section15 performs the display control of the display panel 111 so that theimage display on the display panel 111 (the display surface S1) sidebegins (step S103). Next, the display control section 15 performs thedisplay control so that the image display on this display panel 111 sideis fixed (step S104). The display control section 15 then performs thedisplay control of the display panel 111 so that information display(e.g., the information indicating “power consumption increasing” or“high definition image quality mode starting”, as described above) onthis display surface S1 begins (step S105).

Next, the display control section 15 performs the display control of thedisplay panel 111 so that the information display on this displaysurface S1 ends (step S106 in FIG. 20). It is to be noted that, a periodof this information display is, for example, on the order of a fewseconds. Next, the display control section 15 acquires the operationsignal Sm from the operation sections 12 a, 12 b, and 12 c (step S107).The display control section 15 then determines, based on this operationsignal Sm, whether an instruction, for ending the image display isprovided by the user (step S108). Here, when an instruction for endingthe image display is determined to be provided (step S108: Y), the Howproceeds to step S109 and step S110 (FIG. 24) corresponding to endingprocessing.

In this ending processing, the display control section 15 performs thedisplay control of the display panels 111 and 112, such that the imagedisplay on the display panel 111 (the display surface S1) side ends, andthe image display on the display panel 112 (the display surface S2) sidealso ends (step S109 and step S110 in FIG. 24). Afterward, the powersupply of the electronic apparatus 1 enters the off (OFF) state, and theseries of steps in the display control illustrated in FIG. 19 to FIG. 24ends.

On the other hand, when an instruction for ending the usage display isdetermined not to be provided in step S108 (step S108: N), the displaycontrol section 15 then determines which one of the first to thirddisplay modes is the selected display mode, based on the operationsignal Sm (step S11). It is to be noted that, here, the display surfaceS1 is in the state of facing upward, and therefore, one display modeamong the first to third display modes is settable, as described above.

Here, when the first display mode is determined to be selected in stepS111, the first display mode is already established in this state wherethe display control for the display panel 112 is not performed (thedrive voltage Vd2 is not supplied), and therefore, the flow returns tostep S101 (FIG. 19).

Alternatively, when the second display mode is determined to be selectedin step S111, the display control section 15 performs the displaycontrol of the display panel 112 so that this second display modebegins. Specifically, as described above, the image display is caused tobegin on this display panel 112 side so that the entire pixel region isin the single-color reflection display state in the display panel 112(step S112). The second display mode thus begins, and then the flowreturns to step S101 (FIG. 19).

Alternatively, when the third display mode is determined to be selectedin step S111, the display control section 15 performs the displaycontrol of the display panel 112 so that this third display mode begins.Specifically, as described above, the image display is caused to beginon this display panel 112 side so that the partial single-colorreflection display and the transparent state are established in thedisplay panel 112 (step S113). The third display mode thus begins, andthen the flow returns to step S101 (FIG. 19).

Here, when the display surface S1 is determined not to be in the stateof facing upward in step S102 (step S102: N), the display controlsection 15 then performs the following determination, based on theoperation signal Sm. That is, it is determined whether the displaysurface S2 is in the state of facing upward (step S114 in FIG. 21).

Here, when the display surface S2 is determined not to be in the stateof facing upward (a surface other than the display surfaces S1 and S2 isin the state of facing upward) (step S114: N), the display controlsection 15 then acquires the operation signal Sm again from theoperation sections 12 a, 12 b, and 12 c (step S115). Next, based on thisoperation signal Sm, the display control section 15 determines whetheran instruction for executing the image display on both of the displaysurfaces S1 and S2 (bidirectional display, or double-sided display) isprovided by the user (step S116). Here, when an instruction, forexecuting the bidirectional display is determined not to be provided(step S116: N), the flow returns to the first step S101 (FIG. 19).

On the other hand, when an instruction for executing the bidirectionaldisplay is determined to be provided (step S116: Y), the display controlsection 15 performs the display control of the display panels 111 and112 so that this bidirectional display begins. Specifically, first, thedisplay control section 15 performs the display control of the displaypanel 111 so that fixing of the image display on the display panel 111(the display surface S1) side is canceled (step S117). Next, the displaycontrol section 15 performs the display control of the display panels111 and 112, such that the image display on the display panel 111 sidebegins, and the image display on the display panel 112 (the displaysurface S2) side also begins (step S118 and step S119). Thebidirectional display thus begins, and then the flow returns to stepS101 (FIG. 19).

Here, when the display surface S2 is determined to be is the state offacing upward in step S114 (step S114: Y), the display control section15 performs the display control of the display panel 112 so that theimage display on the display panel 112 (the display surface S2) sidebegins (step S120). Next, the display control section 15 performs thedisplay control so that the image display on this display panel 112 sideis fixed (step S121). Next, the display control section 15 performs thedisplay control of the display panel 112 so that information display(e.g., the information indicating “power consumption decreasing” or“carry mode starting” as described above) on this display surface S2begins (step S122).

Next, the display control section 15 performs the display control of thedisplay panel 112 so that the information display on this displaysurface S2 ends (step S123 in FIG. 22). It is to be noted that, a periodof this information, display is also, for example, on the order of a fewseconds. Next the display control section 15 acquires the operationsignal Sm from the operation sections 12 a, 12 b, and 12 c (step S124).The display control section 15 then determines, based on this operationsignal Sm, whether an instruction for ending the image display isprovided by the user (step S325). Here, when an instruction for endingthe image display is determined to be provided (step S125: Y), the Howproceeds to the ending processing (step S109 and step S110 in FIG. 24)described above.

On the other hand, when an instruction for ending the image display isdetermined not to be provided (step S123: N), the display controlsection 15 then, determines whether the fourth display mode is selected,based on the operation signal Sm (step S126). It is to be noted that,here, the display surface S2 is in the state of facing upward, andtherefore, one display mode among the fourth to sixth display modes issellable, as described above.

Here, when the fourth display mode is determined to be selected, thefourth display mode is already established in this state where thedisplay control for the display panel 111 is not performed (the drivevoltage Vd1 is not supplied), and therefore, the flow returns to stepS101 (FIG. 19).

On the other hand, when the fourth display mode is determined not to beselected, the display control section 15 then acquires the environmentalilluminance Di detected in the illuminance sensor 14 (step S127). Thedisplay control, section 15 then determines whether this environmentalilluminance Di is less than a predetermined, threshold Dth (Di<Dth)(step S128 in FIG. 23). It is to be noted that, this threshold Dth is,for example, an environmental illuminance set as a criterion fordetermining whether reading in outside light is possible. However, thisthreshold Dth is not limited to a fixed value, and may be a variablevalue that is changeable to an arbitrary value depending on thesituation. Here, when the environmental illuminance Di is determined tobe the threshold Dth or greater (Di≥Dth) (step S128: N), theenvironmental illuminance is relatively high (a relatively bright lightenvironment), and therefore, the fourth display mode is automaticallyselected (set) for the reason described above. Therefore, afterward, asdescribed above, since the fourth display mode is already established inthis state, the (low returns to step S101 (FIG. 19).

On the other hand, when the environmental illuminance Di is determinedto be less than the threshold Dth (Di<Dth) (step S128: Y), theenvironmental illuminance is relatively low (a relatively dark lightenvironment), and therefore, the fifth or sixth display mode isautomatically selected for the reason described above. In this case, thedisplay control section 15 next performs the display control of thisdisplay panel 112 so that color tone correction in the image display onthe display panel 112 (the display surface S2) side is performed (stepS129). The display control section 15 then performs the display controlof this display panel 111, such that the image display on the displaypanel 111 (the display surface S1) side begins, as a precondition forstarting the display mode in the fifth or sixth display mode (stepS130).

Next, based on the operation signal Sm acquired in step S124, thedisplay control section 15 determines whether the fifth display mode isselected (step S131). Here, when the fifth display mode is determined tobe selected (step S131: Y), the display control section 15 performs thedisplay control of the display panel 111 so that tins fifth display modebegins. Specifically, as described above, the image display on thisdisplay panel 111 side is changed so that the entire pixel region is inthe single-color display state in the display panel 111 (step S132). Thefifth display mode thus begins, and then the flow returns to step S101(FIG. 19).

On the other hand, when the sixth display mode is determined to beselected (step S131: N), the display control section 15 performs thedisplay control of the display panel 111 so that this sixth display modebegins. Specifically, the image display on this display panel 111 sideis changed so that the partial single-color display state and thetransparent state are established in the display panel 111 as describedabove (step S133). The sixth display mode thus begins, and then the flowreturns to step S101 (FIG. 19). This ends the description of the seriesof steps in the display control illustrated, in FIG. 19 to FIG. 24.

As described above, in the present embodiment, the two types of thedisplay panels 111 and 112 are provided in the display section 11, andtherefore, it possible to implement the image display on the displaysurfaces S1 and S2 facing each other, by allowing the device functionsin the respective display panels 111 and 112 to complement each other.Therefore, an improvement in the convenience of the user can beachieved.

In addition, since such image display (the double-sided display) on thedisplay surfaces S1 and S2 is enabled, it is possible to enlarge adisplay area in the display section 11 (the electronic apparatus 1) to alarge extent. Accordingly, it is possible to display information withmany added value, so that a further improvement in the convenience ofthe user can be achieved.

Moreover, for example, when the display panel 111 and the display panel112 display the respective different images overlapping each other, itis possible to display information with more added values, so that afurther improvement in the convenience of the user can be achieved.

2. Modifications

Next, modifications (Modification 1 and Modification 2) of theabove-described embodiment will be described. It is to be noted that,the same components as those in the above-described embodiment will beprovided with the same reference numerals as those of the embodiment,and the description thereof will be omitted as appropriate.

Modification 1

(Configuration)

FIG. 25 schematically illustrates a configuration example of anelectronic apparatus (an electronic apparatus 1A) with a display deviceaccording to Modification 1, in a plan view (an X-Y plan view). In theelectronic apparatus 1A (the display device) of the presentmodification, the display section 11 is configured to be foldable in two(two display regions) (see an arrow P3 in FIG. 25). Specifically, thisdisplay section 11 is configured to include a display section 11 a (afirst display section), a display section 11 b (a second displaysection), and a hinge section 110.

As with the display section 11 described in the embodiment, the displaysection 11 a has such a configuration that the display panel 111disposed on the display surface S1 side and the display panel 112disposed on the display surface S2 side are overlaid with each other ina thickness direction (a Z-axis direction). Similarly, the displaysection 11 b also has such a configuration that the display panel 111disposed on the display surface S1 side and the display panel 112disposed on the display surface S2 side are overlaid with each other ina thickness direction. It is to be noted that, in this example, ineither of the display sections 11 a and 11 b, the display panels 111 and112 are disposed so that the display surface S1 faces inward whereas thedisplay surface S2 faces outward, in a state where the entire displaysection 11 is folded (a closed state).

The hinge section 110 is a part provided to connect the two displaysections 11 a and 11 b in a foldable manner (free open-close). In thisexample, the hinge section 110 is disposed to extend in a Y-axis so thata rotation shaft in folding (opening and closing) corresponds to theY-axis.

(Action and Effect)

In the electronic apparatus 1A having such a configuration, a similareffect by a similar action to those of the electronic apparatus 1 of theembodiment can be basically obtained.

In addition, in this electronic apparatus 1A, in particular, since thedisplay section 11 is foldable in two, various display manners to bedescribed below can be implemented depending on, for example, the usesituation, so that a further improvement in the convenience of the usercan be achieved.

Specifically, for example, as illustrated in FIG. 26A, when a statewhere the display sections 11 a and 11 b are folded and closed isdetected, the display control section 15 performs, for example, thefollowing display control. That is, the display control section 15performs the above-described display control so that the entire pixelregion in each of these display sections 11 a and 11 b is in thetransparent state in each of the display panels 111 and 112.

It is to be noted that, whether the display sections 11 a and 11 b arein the state of being folded (whether the closed state or an openedstate) is detected, for example, based on a mechanism state in the hingesection 110, and, for example, a detection signal indicating the statesthereof is supplied to the display control section 15.

In this example illustrated in FIG. 26A, the display sections 11 a and11 b are both in the transparent state (the light transmission state).Therefore, for example, in a state such as the standby state of theelectronic apparatus 1A (the display device), the entire display section11 is a panel that is transparent when viewed from either of the frontand the back, so that a display design with an advanced brightnessimpression can be implemented. In addition, in this case, the fourdisplay panels (two for the display panel 112, and two for the displaypanel 111) are overlaid with each other as a whole in the displaysection 11, and therefore, the following effect can also be expected bysetting, for example, any one of the first, third, fourth, and sixthdisplay modes, in each of the display sections 11 a and 11 b. In otherwords, it is possible to display information with more added values, bydisplaying three or four types of different images overlapping eachother. Moreover, it is possible to achieve a further improvement in theconvenience of the user, by displaying the same three or four imagesoverlaid with each other.

Further, for example, as illustrated in FIG. 26B, when a state where thedisplay sections 11 a and 11 b are opened in an up-down direction (avertical direction, or a Y-axis direction in this example) with thehinge section 110 interposed therebetween is detected, the displaycontrol section 15 performs, for example, the following display control.That is, the display control section 15 performs the above-describeddisplay control so that the image display by the transparent state inthe display surface S1 or the display surface S2 (the display surface S1in this example) is performed in one of the display sections 11 a and 11b (the display section 11 a in this example). Specifically, the displaycontrol of the display panels 111 and 112 in the display section 11 a isperformed so that, for example, the image display by any one of thefirst, and third, fourth, and sixth display modes (the first or thirddisplay mode m this example) is performed. In addition, the displaycontrol section 15 performs the above-described display control on theother one (the display section 11 b in this example) so that the imagedisplay by the non-transparent state is performed on the display surfaceS1 or the display surface S2 (the display surface S1 in this example).Specifically, the display control of the display panels 111 and 112 inthe display section 11 b is performed so that, for example, the imagedisplay by the second or fifth display mode (the second display mode inthis example) is performed.

In this example illustrated in FIG. 26B, the image display by thetransparent state is performed in the display section 11 a, and theimage display by the non-transparent state is performed in the displaysection 11 b, and therefore, for example, various use manners such asone to be described below are implemented, so that a further improvementin the convenience of the user can be achieved. Specifically, forexample, when a small camera image sensor (e.g., an image pickup devicesuch as a CMOS (Complementary Metal-Oxide-Semiconductor)) is disposed onthe display surface S2 side in the display section 11 a or the displaysection 11 b, the following use manner can be implemented. That is, forexample, it is possible to implement a use manner, which displaysscreens for various applications in the display section 11 b, whileutilizing the display section 11 a as an electronic viewfinder (with ahigh-definition large screen) in image pickup.

On the other hand, for example, as illustrated in FIG. 26C, when a statewhere the display sections 11 a and 11 b are opened in a lateraldirection (a horizontal direction, an X-axis direction in this example)with the hinge section 110 interposed therebetween is detected, thedisplay control section 15 performs, for example, the following displaycontrol. That is, the display control section 15 performs theabove-described display control so that the image display by thenon-transparent state is performed on a common display surface (thedisplay surface S1 in this example), which is one of the display surfaceS1 and the display surface S2, in each of these display sections 11 aand 11 b. Specifically, the display control of the display panels 111and 112 in each of the display sections 11 b and 11 b is performed sothat, for example, the image display by the second or fifth display mode(the second display mode in this example) is performed.

In this example illustrated in FIG. 26C, the image display by thenon-transparent state is performed on the common display surface (thedisplay surface S1) in each of the display sections 11 a and 11 b, andtherefore, for example, various use manners such as one to be describedbelow are implemented, so that a further improvement in the convenienceof the user can be achieved. Specifically, for example, by using thefirst to sixth display modes, while performing the single image display(large-screen display achieved by combining the two display surfaces S1)on the entire common display surface in these display sections 11 a and11 b, a further improvement in the convenience of the user can beachieved.

Modification 2

FIG. 27A and FIG. 27B each schematically illustrate a configurationexample of an electronic apparatus (an electronic apparatus 1B) with adisplay device according to Modification 2, in a perspective view. Inthe electronic apparatus 1B (the display device) of the presentmodification, components such as the display panels 111 and 112 in thedisplay section 11 have flexibility and are configured as a thinflexible display. Further, in this example, the entire electronicapparatus 1B including the housing 10 exhibits flexibility.

Therefore, storing and carrying this electronic apparatus 1B in a stateof being folded (in a state such as the standby state) when not in useare implemented, for example, as illustrated in FIG. 27A (see an arrowP4 in FIG. 27A). In addition, when, for example, each of the displaypanels 111 and 112 in the display section 11 is set in the transparentstate (the light transmission state) as described above, a see-throughfolding state can be implemented in such a time when not in use, forexample, as illustrated in FIG. 27A.

On the other hand, using this electronic apparatus 1B according to anarbitrary curve degree (a deflection state, or a bending state)including a flat state is implemented when in use (in the imagedisplay), for example, as illustrated in FIG. 27B. In addition, in thiscase as well, the image display can be performed by arbitrarily settingone display mode among the plurality of types of display modes (thefirst to sixth display modes) described above.

Here, in this electronic apparatus 1B, each of the display panels 111and 112 in the display section 11 has a configuration using a flexiblesubstrate such as a resin film, in place of the glass substrate.Further, each device such as the drive device is configured using aflexible device such as an organic TFT. The housing 10 is an outermember having flexibility as well. Specifically, this housing 10 is madeof a material such as a resin film (a transparent film), which is softand has transparency (optical transparency) for display lightexemplified by an olefin resin.

In the electronic apparatus 1B having such a configuration, a similareffect by a similar action to those of the electronic apparatus 1 of theembodiment can be basically obtained.

In addition, in particular, in this electronic apparatus 1B, since eachcomponent such as the display panels 111 and 112 has flexibility, forexample, the above-described various use manners and display manners canbe implemented, so that a further improvement in the convenience of theuser can be achieved.

3. Other Modifications

Technology of the present disclosure is described above using theembodiment and modifications, but the present technology is not limitedto these embodiments and the like, and may be variously modified.

For example, the embodiment and the like are described using, as anexample, the case where one of the three types of display modes (thefirst to third display modes, or the fourth to sixth display modes) isselected, but are not limited thereto. In other words, one display modemay be selected, from arbitrary two types of display modes among thesethree types of display modes. In addition, the way of selecting thedisplay mode in these cases is not limited to the ways described in theembodiment and the like, and one of the plurality of types of displaymodes may be selected (changed) using other way.

Moreover, the plurality of types of display modes also are not limitedto the six types of display modes (the first to sixth display modes)described in the embodiment and the like, and other type of display modemay be added (or alternatively provided) and used.

Further, the embodiment and the like are described using the specifictype, configuration, and the like of each of the light emitting elementand the light control element each serving as the display element ineach of the display panels, but are not limited thereto. For example, alight emitting element other than the organic EL device and a lightcontrol element other than the liquid crystal device, using thecholesteric liquid crystal may each be used as the display element. Inaddition, the light emitting element may perform color image display, byusing, for example, a light emitting element emitting white light and athree-primary color filter (disposed both above and below the lightemitting element in this case), instead of performing the emission ofeach color in the three primary colors (R, G, B). Moreover, in somecases, the image display in each display panel may be monochrome imagedisplay, not the color image display described in the embodiment and thelike.

In addition, the Modification 1 is described above using, as an example,the case where the display section is foldable in two (the displaysection includes the foldable two display sections), but is not limitedthereto. In other words, for example, the display section may befoldable in three or more (the display section may include three or morefoldable display sections).

Further, the embodiment and the like are described using the specificconfigurations of the electronic apparatus and the display device, butare not limited to those configurations. Specifically, for example,these configurations may be partially replaced with other configuration,or other configuration may be further added. In addition, any shape,layout, quantity, material, and the like in each configuration are alsonot limited to those described in the embodiment and the like, and othershape, layout, quantity, material, and the like may be adopted.

Furthermore, the various examples described above may be arbitrarilycombined and appropriately used.

In addition, the display device of the present disclosure may be appliednot only to the mobile apparatus descried as an example of theelectronic apparatus in the embodiment and the like, but also to othervarious mobile apparatuses (e.g., an electronic book, a notebook PC(Personal computer), a mobile audio layer, a mobile movie player, amobile phone, a wearable terminal, and the like). Moreover, the displaydevice of the present disclosure may be applied not only to such amobile apparatus but also to various electronic apparatuses (e.g., a TVapparatus (a TV receiver), an illumination apparatus, a display devicebuilt in a window, a mirror, or the like, an electronic sign (DigitalSignage), a car navigation system, and the like).

It is to be noted that, the effects described in the present,specification are only examples and not limitative, and there may beother effects.

It is to be noted that the present technology may also have thefollowing configurations.

(1) A display device, including:

display section having a first display surface and a second displaysurface facing each other,

wherein the display section includes

a first display panel disposed on the first display surface side, andincluding a plurality of light emitting elements, and

a second display panel disposed on the second display surface side, andincluding a plurality of light control elements each performing lightcontrol for control of transmission or reflection of incident lightperforating reflective image display utilizing reflection of theincident light.

(2) The display device according to (1), wherein

the light emitting element outputs emission light toward both of thefirst and second display surface sides, and

the light control element performs the light control and the reflectiveimage display, for both of the incident light from the first displaysurface side and the incident light from the second display surfaceside.

(3) The display device according to (2), wherein in each of the firstand second display panels, optical transparency changes on apixel-by-pixel basis, according to a drive voltage applied to the lightemitting element or the light control element.

(4) The display device according to (3), further including a displaycontrol section configured to perform individual control of imagedisplay in the first and second display panels,

wherein the display control section performs the individual control toexecute one display mode selected from a plurality of types of displaymodes utilizing a change in the optical transparency on thepixel-by-pixel basis.

(5) The display device according to (4), wherein

when image display by the light emitting element is performed, in atleast a portion of the pixel region of the first display panel,

the display control section performs the individual control to executeone display mode selected from at least two or more types of displaymodes among three types of display modes serving as the plurality oftypes of display modes, the modes comprising:

a first display mode in which an entire pixel region of the seconddisplay panel is in a transparent state, by utilizing the transmissionof the incident light by the light control element,

a second display mode in which the entire pixel region of the seconddisplay panel is in a single-color reflection display state, byutilizing the reflective image display based on the incident light fromthe first display surface side by the light control element, and

a third display mode in which, in the second display panel, a vicinityof a pixel region corresponding to a display pixel region in the firstdisplay panel is in the single-color reflection display state, and avicinity of a pixel region corresponding to a transparent pixel regionthat is a non-display pixel region in the first display panel is in thetransparent state.

(6) The display device according to (5), wherein

setting of color in the single-color reflection display state in thesecond and third display modes, and

setting of a portion of a pixel region to be in the single-colorreflection display state or the transparent state in the third displaymode

are each arbitrarily adjustable,

(7) The display device according to (5) or (6), wherein front the atleast two or more types of display modes among the first to thirddisplay modes, the one display mode is selected according to anoperation signal input from outside.

(8) The display device according to any one of (5) to (7), wherein whena state where the first display surface faces upward is detected,

the display control section performs the individual control to performthe image display in at least a portion of the pixel region of the firstdisplay panel.

(9) The display device according to any one of (4) to (8), wherein

when the reflective image display based on the incident light from thesecond display surface side by the light control element is performed,in at least a portion of the pixel region of the second display panel,

the display control section performs the individual control to executeone display mode selected from at least two or more types of displaymodes among three types of display modes serving as the plurality oftypes of display modes, the modes comprising:

a fourth display mode in which an entire pixel region of the firstdisplay panel is in a transparent state by the light emitting elemententering a non-emission state,

a fifth display mode in which the entire pixel region of the firstdisplay panel is in a single-color display state by the light emittingelement entering an emission state, and

a sixth display mode in which, in the first display panel, a vicinity ofa pixel region corresponding to a display pixel region in the seconddisplay panel is in the single-color display state, and a vicinity of apixel region corresponding to a transparent pixel region that is anon-display pixel region in the second display panel is in thetransparent state.

(10) The display device according to (9), wherein

setting of color in the single-color display state in the fifth andsixth display modes, and

setting of a portion of a pixel region to be in the single-color displaystate or the transparent state in the sixth display mode

are each arbitrarily adjustable.

(11) The display device according to (9) or (10), wherein from the atleast two or more types of display modes among the fourth to sixthdisplay modes, the one display mode is selected according to anoperation signal input from outside or a defected environmentalilluminance.(12) The display device according to (11), wherein

the fourth display mode is selected as the one display mode, when theenvironmental illuminance is equal to or greater than a threshold, and

the fifth or sixth display mode is selected as the one display mode,when the environmental illuminance is less than the threshold.

(13) The display device according to any one of (9) to (12), wherein

when the second display surface being in a state of facing upward isdetected, the display control section performs the individual control toperform the reflective image display in at least a portion of the pixelregion of the second display panel.

(14) The display device according to any one of (4) to (13), wherein

when the display device being in a standby stale is detected,

the display control section performs the individual control to allow apixel region, in each of the first and second display panels to be in atransparent state.

(15) The display device according to any one of (1) to (14), wherein

the display section includes

a first display section and a second display section each having thefirst and second display panels, and

a hinge section configured to connect the first and second displaysections in a foldable manner.

(16) The display device according to (15), wherein

when the first and second display sections being in a folded and closedstate is detected,

in each of the first and second display sections, display control isperformed to allow a pixel region in each of the first and seconddisplay panels to be in a transparent state.

(17) The display device according to (15) or (16), wherein

when a state where the first and second display sections axe opened inan up-down direction with the hinge section interposed therebetween isdetected,

display control is performed to perform image display by a transparentstate in the first or second display surface, in one of the first andsecond display sections, and to perform image display by anon-transparent state in the first or second display surface, in theother one, and

when a state where the first and second display sections are opened in alateral direction with the hinge section interposed therebetween isdetected,

display control is performed to perform image display by anon-transparent state in a common display surface that is one of thefirst and second display surfaces, in each of the first and seconddisplay sections.

(18) The display device according to any one of (1) to (17), wherein thefirst and second display panels each have flexibility.

(19) The display device according to any one of (1) to (18), wherein

the light emitting element is an organic electroluminescence element,and

the light control element comprises cholesteric liquid crystal.

(20) An electronic apparatus, including:

a display device,

wherein the display device includes

a display section having a first display surface and a second displaysurface facing each other, and

the display section includes

a first display panel disposed on the first display surface side, andincluding a plurality of light emitting elements, and

a second display panel disposed on the second display surface side, andincluding a plurality of light control elements each perforating lightcontrol for control of transmission or reflection of incident lightperforming reflective image display utilizing the reflection of theincident light.

The present application is based on and claims priority from JapanesePatent Application No. 2013-197791 filed in the Japan Patent Office onSep. 25, 2013, the entire contents of which is hereby incorporated byreference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

The invention claimed is:
 1. A display device, comprising: a displaysection, wherein the display section comprises a first display surfacethat faces a second display surface of the display section, wherein thedisplay section includes: a first display panel on the first displaysurface, and the first display panel includes a plurality of lightemitting elements, and a second display panel on the second displaysurface, wherein the second display panel includes a plurality of lightcontrol elements, and wherein a light control element of the pluralityof light control elements is configured to: control one of transmissionof incident light or reflection of the incident light; and controldisplay of a reflective image based on the reflection of the incidentlight, wherein each of the first display panel and the second displaypanel is configured to change optical transparency for at least one of afirst pixel of the first display panel or a second pixel of the seconddisplay panel, and wherein the optical transparency is changed based ona drive voltage which is applied to at least one of a light emittingelement of the plurality of light emitting elements or the light controlelement.
 2. The display device according to claim 1, wherein the lightemitting element is configured to output emission light towards at leastone of a first side of the first display surface or a second side of thesecond display surface, and the light control element is furtherconfigured to control the incident light and control the display of thereflective image, for the incident light from the first side of thefirst display surface and the incident light from the second side of thesecond display surface.
 3. The display device according to claim 1,further comprising a display control section configured to: controldisplay of a first image in the first display panel and control displayof a second image in the second display panel; and control execution ofa first selected display mode selected from a plurality of types ofdisplay modes, wherein the first selected display mode is executed basedon the change in the optical-transparency.
 4. The display deviceaccording to claim 3, wherein the display control section is furtherconfigured to control execution of the first selected display modeselected from at least two types of display modes among three types ofdisplay modes, wherein the three types of display modes serve as theplurality of types of display modes, and wherein the first display modeis executed based on the display of the first image in at least a firstportion of a first pixel region of the first display panel, the threetypes of display modes comprising: a first display mode in which asecond pixel region of the second display panel is in a transparentstate, wherein the transparent state of the second pixel region is basedon the transmission of the incident light by the light control element,a second display mode in which the second pixel region of the seconddisplay panel is in a single-color reflection display state, wherein thesingle-color reflection display state of the second pixel region isbased on the display of the reflective image, and wherein the reflectiveimage is displayed based on the incident light reflected from first sideof the first display surface by the light control element, and a thirddisplay mode in which: a third pixel region of the second display panelcorresponding to a display pixel region in the first display panel is inthe single-color reflection display state, and a fourth pixel region ofthe second display panel corresponding to a transparent pixel region inthe first display panel is in the transparent state, wherein thetransparent pixel region is a non-display pixel region in the firstdisplay panel.
 5. The display device according to claim 4, wherein thedisplay control section is further configured to: adjust a setting ofcolor in the single-color reflection display state in the second displaymode and the third display mode, and adjust the setting of a thirdportion of a fifth pixel region to correspond to one of the single-colorreflection display state or the transparent state in the third displaymode.
 6. An electronic apparatus, comprising: a display device, whereinthe display device includes a display section, wherein the displaysection comprises a first display surface that faces a second displaysurface of the display section, the display section includes: a firstdisplay panel on the first display surface, and the first display panelincludes a plurality of light emitting elements, and a second displaypanel on the second display surface, wherein the second display panelincludes a plurality of light control elements, and wherein a lightcontrol element of the plurality of light control elements is configuredto: control one of transmission of incident light or reflection of theincident light; and control display of a reflective image based on thereflection of the incident light, and wherein each of the first displaypanel and the second display panel is configured to change opticaltransparency for at least one of a first pixel of the first displaypanel or a second pixel of the second display panel, and wherein theoptical transparency is changed based on a drive voltage which isapplied to at least one of a light emitting element of the plurality oflight emitting elements or the light control element.